Cyclospora cayetanesis was identified as a coccidian in 1993 was Dr. Ynes Ortega, a Peruvian investigator who named the organism for Caytenao Heredia, the university in Peru where the work was performed. In sites in Peru, Guatemala, and Nepal, Cyclospora has been shown to be a fairly common enteric pathogen among children living in poor communities. Large outbreaks in North America in 1996, 1997 and 1998 have been linked to imported fresh produce. The overall aim of this study is to apply the newly developed tools of Cyclospora ELISA and Immmunoblot assay, PCR-based detection in stool specimens. In stool specimens, water and sewage, and molecular genotyping to further our understanding of the epidemiology of Cyclospora cayetanensis. Specifically we will 1, validate the performance of the Cyclospora ELISA and immunoblot assay under field conditions; 2, validate the use of PCR in field studies as a sensitive and specific method to detect Cyclospora in stool specimens, water and sewage; and 3, determine the sensitivity of PCR performed on rectal swab specimens as a detection method compared to PCR and microscopic examination of whole stool specimens. To better define the epidemiology of Cyclospora we will identify factors associated with Cyclospora infection over different ecologic zones, variations in socioeconomic status, and within an endemic community, and examine genotype variations in families with more than one infection, and in individuals infected more than once. Under the TMRC program approach, this component will primarily emphasize the use of new techniques (molecular epidemiology, immunological assays, GPS/GIS) towards the characterization of the epidemiology and transmission of Cyclospora.